These are Mega Man-esque side scrollers, with the most famous of the four being Asakura! P, which is a challenging puzzle-platformer. The third game is larger and has more of Metroidvania structure to it compared to the others. Definitely worth looking into if you like indie Japanese action platformers.
The games are in Japanese, but they're simple enough that there isn't a language barrier issue, except for knowing what some of the items do in the third game, but those can typically be figured out anyway.
Additionally, Asakura! P has an English Patch than can be found here: https://tlwiki.org/?title=Asakura_P